Optical system of variable magnification.



M. LANGE. OPTlCAL SYSTEM or VARIABLE MAGNIFICAHON APPLICATION FILED NOV-JO: HIM

Patented Aug. 14, 1917.

llIIlIl/I/ Ill I 1 n1 M. LANGE. oFncAL SYSTEM or VARIABLE mcmrlcmou.

APPLICATION FILED NOV. H- "I4.

Patented Aug. 14, 1917.

2 ENNIS-SHUT 2.

UNITED ST ATES PATENT OFFICE.

BERLIN, GERMANY.

OPTICAL SYSTEM OF VARIABLE MAGNIFICATION.

Specification of Letters Patent.

Patented Aug. 14, 1917.

Appllcatlonllled November 14, 191i. Bcrlal No. 872,203.

T 0 all whom. it may concern:

Be it known that I, Dr. Max Lanes, a citiZen of the German Empire, and resident of Steglitz, near Berlin, (iermany have invented certain new and useful improve ments in Optical Systems of Variable Magnification, of which the following is a specification.

This invention relates to an optical system with reversible lens system consisting at least of twoparts for varying or changing the magnification. The invention has for its object in optical systems of this kind to enable a great variation of magnification in connection with favorable aperture conditions or small length or with both these properties.

The objects of the invention are attained in that a. reversible lens system is provided which has a limited focal length and which is so disposed behind the objective, i. e. the li ht admission lens in the path of nonparal e1 rays that its center of rotation coincides with the central point between its ob- 'ect-plane,-i. e. the image plane of the oi:- JectiVe and its own image plane and therefore has equal distance from both said planes and that the center of rotation is at the same time laterally displaced from the center between its two main planes.

In connection with optical systems having a reversible lens system for the change of magnification, there frequently exists a certain defect in that the reversible lens system requires a casing of undesired large dimensions at the place where the lens system is disposed. It is therefore important to arrange the reversible lens system in such a manner thatit does not require a bulky .form of raising. A suitable form of the reversible lens system results by composing it of a positive and a negative element and arranging it in such manner that the point lyingjn-the middle between its nodal points is on-anouter side of the reversible system while the center of rotation is between the twoelements. If in such construction the object plane of the reversible system, i. c. the-image plane of the objective is virtual, it 'is' possible to dispose the reversible systernquite close to the objective. This is advantageous especially for periscopes in that the'reversible part is close to the entranceother, so that depending from the one or the other system icing inserted in the path of rays, a. repeated variation of he magnification is possible.

The invention is shown on the accompany ing drawings on several constructional fomis of telescopes.

Figure 1 represents a straight-sight telescope with two real image planes;

Fig. 2 represents a straighosight telescope with a virtual and a real image plane;

Fig. 3 represents a telescope with a refracted axis and a virtual and a real image plane;

Fig. 4 is a modification of the reversing system used in the constructional fonn ac cording to Fig. 3;

Fig. 5 represents a straight-Si h telescope with two real image planes anlftwo revels ing systems adapted to be inserted in the path of rays.

In the telescope shown in Fig. 1, the ob- 'ecti\'e is designated with the numeral 1;

hind the objective. is a diaphragm 2 on the object side of the reversing system composed of anegative element 3 an a positive element 4. The center between the main points of the reversing system is indicated at 5. The reversing system is provided within a separate asing 6 adapted to he turned about a shaft 7 located between the lenses 3, 4. Atthis point. the telescope casing 8 has an enlurgemcnt 9. 10 is the ocular. The diaphragm on the ocular side of the reversing system is indicated at 11. The axis of re tation 7 is'equidistant from 2 and 11.

-In the constructional form according to Fig. 2 the casing of the instrument. is designated 8': the part of the casing adapted to receive the reversing system is designated 6' and 9' is the enlargement of the casing. The objective, which in this case has negative focal length, is designated 1' and 8. 4 are the two elements of the reversingsystern. The virtual image lane of thc'negative objective is indicated at 2'; the image plane of the compound system formed by tlu obje tive and the reversing system is at II. The axis of rotation of the reversing system is indicated at T' and the center between the two main points is indicated at 5'. I is the ocular and 12 another stationary |-e\ersingsystem, which casts the image into the imam,- plaue of the ocular.

In Fig. 2} the use of the system corresponding to Fig. 2 is shown on a telescope with two bends. The objective is designated 1". The virtual image plane. of the negative objecti e is indicated at 2". The objeetive is directly followed by the reversing system 3","4, which through the medium of a |)l'i.-ltl 13 produces between its two lenses a bend in the path of the rays. The reversing system 3", 4", l3 is mounted on a rot alahle carrier 14, which is of such small dimensions that there is no enlargement of the instrument casing at this point. The carrier H is pivoted on the journal 15 so that, the element 3" or -'L" of the reversing system ean be turned toward the objective. to is the collective element and 11" the image plane on the ocular side of the reversible system. 10" is the ocular which produces by means of the prism 18 between its collective element. and its outer lens a second bend in the path of rays. 17 is a stationary reversing system arranged between the diaphragm 11" and the ocular 10. The reversing system 17 casts the image from 11" toward the ocular.

The rotation of the carrier, containing the reversinizsystem it" 4" about the journal 15 may be replaced by a rotation about an axis vertical to the optical axes of the elements 0 the reversing system. In this case the. elements of the revel-sin system must be. doubled. as shown In Fig. 4, where. the two sets of reversin" systems are designated 3', J", prism 1 5" am 15'. -l" and prism 12''".

Fig. 5 is identical with the on tructional l'ornl according to Fig. l except that two dillerent i'e\e|'sin; systems are provided in the part 6" of the easin namely, the. reversing sy 'tems it", 4 ill 3'', t". Each of these reversin systems may Jae disposed in two positions III the path of rays of the instrument so that. altogether four magnifications can be obtained.

What. I claim is:

1. U )tlCtll slvstem comprising an objective, an ocu ar am a reversible system adapted to var the magnification-on reversal, the reversi the system being composed of a positi ve audia. negative element and so arranged that its fulcrum lies between its two elements and the center between its main points on one side, 1'. e. outside the reversible. 5 Stem.

2. Optical system comprising an objective of negative f cal length. an ocular and a reversible system in close proximity to the objective adapted to var the magnification of the system on reversa and so disposed that its fulcrum is equidistant from the image plane of the reversal system on its ocular side and from the virtual image plane of the objective.

In testimony whereof I have signed this specification in the presence of two subscriblug witnesses.

DR. MAX LANGE. Witnesses:

Wowmma Haor'r, Humor Hum. 

